Switching regulated power adapter with extremely wide input voltage range

　　Application of TOP Switch power adapter design design steps and examples There are many reference designs in ponent, and many are even in Chinese. Readers can go directly to the Internet to check. This book does not need to be excerpted, so it is no longer praised. This book is about TOP Switch application The design is a switching stabilized power adapter design with a very wide input voltage range.

　　statement of problem

　　Some portable electronic devices hope that their power adapters can be applied to AC mains in the global voltage range and can be used in cars with 12V and 24VDC batteries.

　　Usually the most convenient solution is to use an AC input port for AC mains, and a dedicated input port for PC for DC12V and 24V. In this way, the input voltage range is relatively small (/V<5), which is easier to implement.

　　However, the users of these electronic devices are not experts in power adapters, or even laymen in electronic technology. It is easy to connect AC mains to the DC port by mistake, causing catastrophic damage to the power adapter.

　　Solution 1

　　In order to solve this problem, a dedicated DC port socket can be used, just like general electronic equipment (such as walkmans, inkjet printers, etc.). In this way, the input of the power adapter adopts a similar input socket method. The line of the special plug is also connected to the AC mains, this way can be used normally.

　　Separate AC and DC input mode: The circuit block diagram of this input mode does not exceed a battery pack voltage level in the input voltage range (such as 12V voltage level: 9~16V, 24V voltage level 18-32V, 36V voltage level 27V-48V, 48V voltage When the voltage level is 40~65V or 38-70V and 110V voltage level 85-150V), the DC input part does not need to be processed, and it is directly sent to the final stage switching power adapter for input, while the AC mains is used to connect the AC through the first stage power adapter The mains power can be changed to the same voltage level as the DC input voltage. In this way, the two-stage power adapter can be an ordinary AC85-264V mains input and a DC voltage input power adapter.

　　For example, an output AC85-264V mains input and DCA8V voltage level input, output 15W, 5V/3A power adapter can adopt a two-stage TOP Switch solution, the first stage converts AC85-264 into any one between DCA40~65V The voltage can be used; DCA8V can be connected with the output of the first stage as the input of the second stage, so that the output voltage of the first stage does not need to be accurate and stable, and the primary-side control method commonly used in flyback converters can be used. You can choose T024, or TOP234 or TP44 for TOPwih. Considering the simplicity and low cost of the circuit, it is better to choose To224Y. It is better to choose the intermittent working mode.

　　The second-level TOP Switch should use 48V voltage level dedicated T0N44 or T0424, use m431 as the voltage feedback error amplifier, and control the control terminal of TOP414 or TOP424 through an optocoupler.

　　Machine parameters:

　　Input voltage: 85~264V (AC)

　　40~65V(DC)

　　Output voltage: 5V

　　Output current: 3A

　　Accuracy: 1%

　　Peak voltage: <50mVp-p, normally less than 30mVp-p

　　Power adapter voltage adjustment rate: <1%

　　Load current adjustment rate: <1%

　　Efficiency: not less than 50% (AC input), not less than 70% (DC input)

　　Transformer design

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